Update role information

+ Update a comment about user role
Fix a typo in the new ControlInsight role name
Merge pull request #58 from erran/controls-insight-only-comment

Add controls-insight-only as a valid role
Set role.id to -1 by default on initialization

+ Fix #57
Merge pull request #60 from erran/patch-2

Set role.id to -1 by default on initialization. Also #57
Bump to version 0.7.2 for recent Role additions.
Fix updates on Roles.
Merge pull request #61 from kkohli-r7/master

Fix updates on Roles.
Bumping version to pick up Role update fix.
Downcasing default color for tags.
Ensure that role ID is numeric.

If not cast, it is possible for the to_xml call to fail because of
using a String in > 0.
Fixed issued related to improper escaping when sending the role name to load and delete commands.
Merge pull request #62 from rapid7/RoleBugs

Fixes escaping in Roles
Updated the Role class to use REXML Elements instead of creating xml strings manually.
Bumping version to publish Role refactoring/fixes.
Swapping aliases to favor shorter form.

Also adds missing alias for site tags.
Add tag filter to doc
Merge pull request #63 from zachrab/master

Add tag to doc for Filter class.
Ensures tag calls return all tags.

The underlying API call implicitly limits the number of results to only
500. If more than 500 tags exist, only 500 get returned. This is
unprecedented in the gem, so the methods have been modified to return
all results.
Bumping version for next release.